The freedom and convenience afforded by mobile systems have made them very popular, mobile communication networks must be developed or modified rapidly in order to satisfy the growth of mobile network traffic. Therefore, it has created a demand for mobile communication networks that can provide subscribers better quality of service and have no influence by increasing traffic.
FIG. 1 shows the rough illustration of a sample mobile communication network. Taking the cellular system as an example, the geographical coverage area of the mobile communication network is partitioned into cells served by base stations 100. Each mobile station of an individual subscriber is connected to the wireless network via the base stations. The coverage of cells differs greatly according to various factors, such as the power of the base station, the geographical features (e.g. mountains, valleys or rivers) within the cells, the area (e.g. city or suburb) of the cells and the architecture (e.g. tall buildings, railroad or highway) within the cells, etc. One or more cells are respectively combined to a location area 110 (LA) in a GSM system, also known as Paging Area (PA), Routing Area (RA) or Registration Area in other systems. Basically, a location area is a region in which subscribers can move arbitrarily without a location area update (LU) that incurs the central database update (e.g. in a Home Location Register (HLR) or Visitor Location Register (VLR)) of the location area information that is utilized for describing the current location area of subscribers. The size of a location area is defined to cover the demands raised by traffic density and flow, population density and subscriber mobility, etc.
Mobility management enables the wireless network to find the locations of mobile stations so as to deliver incoming calls, messages or packets to mobile stations. Mobility management includes location update, paging and other operations, such as handover, etc., which are related to the location or mobility of subscribers. Since subscribers are free to move within the service area of the system, the system can only maintain the approximate location of each subscriber. When a connection needs to be established for a particular subscriber, the system has to determine the subscriber's exact location, to the accuracy of a cell, within the location area. When a subscriber crosses the border of the specific location area, the mobile station must register its new location area through signaling the location area information to the system. This procedure is called location area updating (LU) or location registration. The updating procedure is for informing the system about the current location area of the subscriber. Besides location area update, there are also other types of location updates that will be described later in this specification. When the system tries to deliver a phone call or message to a subscriber by first finding the location of the specific subscriber, the system can search among the cells within the current location area of the mobile station. This procedure is called paging. The paging procedure is for determining the exact location, to the accuracy of a cell, of the subscriber.
Because there are many tradeoffs and complexity involved, the parameters employed in mobility management are difficult to be defined in an optimal manner. For example, how to define the scope, including the size and the border, of location areas so as to decrease the overall traffic loads of the mobile communication network is an important issue for optimizing mobility management. Since a location area is composed of cells, the size and the border of each location area can be defined by deciding which cells are collected into the location area. If the size of the location area is too small, mobile stations cross the border of the location area frequently. As a result, the mobile stations perform location area updates frequently. The system can thus have lower paging loads. However, the system must waste its resources by performing frequently location area updates, and the mobile station must waste its power to transmit the location area update signal. Alternatively, if the size of the location area is too large, mobile stations cross the border of the location area rarely and do not perform location area updates frequently. However, a large coverage area has to be paged when a call or a message arrives, and thereby the resources of the system are wasted. In addition, the border of the location area is also an important factor in defining the scope of the location area. If the border of the location area is set parallel to and close to major highways, or in heavy traffic regions where population and mobility behavior of the subscribers are heavy loads, the mobile stations may result in many location area updates. Furthermore, the subscribers may cross the border of a specific location area back and forth, thereby causing many location area updates, if the border of the location area is not properly set. As a result, the system wastes its resources by processing frequent location area update procedures, and the mobile stations waste power transmitting the location area update signal.
Various conventional mobility models, such as fluid flow model, gravity mode and random walk model, etc., are presented as a basis for studying issues resulting from subscribers' behavior. For further discussions, please refer to “Location Management for Next-Generation Personal Communications Networks” (pp. 18˜pp.24, IEEE Network, September/October 2000) incorporated herein by reference. Those conventional mobility models most likely are used to study issues for subscribers' behavior, as mentioned, not for the purpose of mobility management optimization in a live mobile communication network so that they are deficient in precision and accuracy to practically optimize a mobility management. Moreover, the methods and models described above don't provide suitable and user-friendly software for users, basically, the user interface thereof is merely for the purpose of engineering-background people to use. Therefore, it is desirable to provide a user interface system that is capable of enabling a user to simply and relatively quickly analyze the status of a mobile network and thereby optimize mobility management for the live mobile network.